|
Post by SeaRat on Apr 18, 2010 18:38:44 GMT -8
In the general discussion area, I just posted a thread about different harness designs. I related a near miss that one of our people suffered due to the military harness. I'd like to use this thread to discuss the military harness, how it is set up, and how to use it. With this discussion, hopefully people will appreciate it's design, and understand its limitations.
John
|
|
|
Post by SeaRat on Apr 18, 2010 19:39:56 GMT -8
Here is the military harness, as was being used at the U.S. Naval School for Underwater Swimmers when I shot this photo with my Nikonos I in 1967. Note that you cannot see the chest straps, but they are being used. Normally we would use the double D-rings to make a quick release, which I'll describe in a subsequent post. However, the idea was to keep the end of the quick release sticking out the neck of our vest so that in an emergency, we could ditch the unit very quickly. We practiced this in the pool with doff-and-don drills, so we could do it anytime needed. I was in the pool today, and did a doff-and-don with my Healthways Scuba regulator on a single tank. But pay attention to the amount of harness being used. We would take the harness, and it should go about six inches above (the top of the loop) the top of the tank's manifold to be adjusted approximately correctly. I just measured my twin 50s with the military harness, and I have mine adjusted to 7 inches above the manifold--I have a pretty thick chest, so that may be a bit much for some, but that's where mine is now. That's a pretty big loop, especially compared to today's harness systems which like a higher tank position. With the military harness, we wanted a lower position so that the tanks would position the regulator between our shoulder blades, and we could easily swim, move arms, etc. We had the bands about six to twelve inches apart (mine right now are at 7 inches apart), which gives enough difference to keep the tanks stable, and allow the waist strap to go around our waist and not our hips. This photo of my dive buddy Bob Means in the U.S. Navy Underwater Swimmers' School (bottom) shows the quick release on his shoulder harness. He is leading the compass course, with the compass on his wrist. The top photo shows more from the same exercise as the one above, and shows the military harness in use. John
|
|
|
Post by nikeajax on Apr 20, 2010 18:48:16 GMT -8
John, can you explain why you like this style of harness so much? What are the advantages, disadvantages if any? Is it a matter of complexity, in that you really have to know your gear? What I know about the military is that they do things, usually, for a reason, and that once you’ve learned something, it stays put, both figuratively and literally, ie, you don’t want that sucker shifting around on ya! I love esoteric knowledge, especially when I can put it to use. It becomes a point of pride when someone tells me that something tried and true is dangerous only because it’s old fashioned. I have people look at me like I’m a madman because I like 1960’s gear, especially with something like Healthways stuff, that no one’s ever heard of, “Well, I don’t know that sounds awfully dangerous…” I usually tell them “If it’s good enough for Jacques Cousteau, it’s good enough for me…” If I live to be 87 using “old fashioned” scuba gear, I’ll be happy! Jaybird
|
|
|
Post by SeaRat on Apr 24, 2010 18:04:56 GMT -8
nikeajax,
You've brought up some good points. First, let me explain that the military harness was not my first one. Actually, I had a 38 cubic foot tank as a teenager which was my first harness, but I do not recall it at all. It worked to keep the tank on my back. My second harness, with the Healthways ScubaStar regulator, was a Healthways plate with a blue harness and quick-release buckles. It has a snap on the shoulder harness. I bought one off e-bay, and so have that harness again. It has a waist strap with a crotch strap that integrates with the waist strap buckle.
It was only when I got into the USAF that I started using the military harness, first at the U.S. Navy School for Underwater Swimmers, where we had twin 90 cubic foot aluminum tanks (3000 psig) made specifically for the Navy. They were big and heavy (see the above photos). Then we used them for our Pararescue jump tanks too, which were smaller 40 cubic foot tanks rated at 2100 psig. They had the normal adjustments for the shoulder straps, the chest strap, the waist strap and the crotch strap. Over this, we put on our parachute harness. Under the scuba harness, we wore underarm life preservers (LPUs) which nobody outside the military knows about (bladders in a bag under each arm, inflated by a 50 gram CO2 cartridge). When we made pararscuba jumps, we would get out of the parachute harness and still have the entire military harness for scuba (until the 1970s, when the parachute harness was integrated into the scuba harness in what Pararescue called the "integrated harness").
So why do I like the military harness now? First, I use it only on double tanks, as this is how I learned to use it (and it doesn't seem to work as well on single tanks). But with doubles, the regulator gets closer to the diver's back and can be worn lower, both of which affect the breathing characteristics of the double hose regulators. It is also very comfortable, as the two tanks ride along the back and buttocks muscles, rather than on the spine and hip bones (which backpacks tend to do when vertical, walking out-of-water).
The military harness is not to be confused with the harnesses that Cousteau and his divers used. They also had adjustable shoulder straps, but many do not realize that the Cousteau divers did not use a waist strap. Instead, they used a hook on the crotch strap that mated to a notch in the buckle of the weight belt, and in effect the weight belt became the waist strap. In one very telling scene from Cousteau's second movie, World Without Sun[/B], Cousteau is seen entering the Starfish House, climbing up the ladder in full gear, and standing fully suited for diving as one of the oceanauts grabs his four-cylinder aqualung. He reaches down, disengages the crotch strap from the weight belt, slides effortlessly out of the shoulder straps (which are mounted at the top and bottom of the cylinders, not on bands as with the military harness), throws the regulator hoses off, and simply walks away from the unit. The shoulder straps in this arrangement are so far apart that they act like stabilizers for the aqualung, keeping it in the correct orientation on the diver.
I hope this gives you a bit of a perspective on how these harnesses work, and why I like the military harness so much. I actually have one set up so that I can go between the military style, my own style (four-point connection with hip straps on my Para-Sea BC), and the Cousteau-style without a waist strap.
John
|
|
|
Post by nikeajax on Apr 26, 2010 12:45:18 GMT -8
John, since you were, always will be, a USAF diver (can I use the term PJ?), I'm sure you did a lot of rescues, but did you ever do any recovery work; did you ever recover anything exotic like say a BOMARC: Were most divers big-boys like you? I can tell those are big tanks by looking at the valves, but not so much by the men, yikes! Jaybird
|
|
|
Post by SeaRat on Apr 28, 2010 22:38:14 GMT -8
Jaybird,
I did not do any of those types of recoveries. We did, while I was in Bermuda and Florida, have a NASA mission involving Apollo recovery, where we trained putting the floatation collar on the Apollo capsule. And yes, I am still a PJ. You don't stop being one just because you are not currently doing that job. It's more of a mindset on how to accomplish things, to "go for it" and get the job done, sometimes against the odds. Most of the guys in Pararescue were not big guys; they were more the wiry types who could run and swim. We did have to carry a lot on our backs, so strength was good, but simply being big was not necessarily an asset. Bob Means, the guy in the underwater photo above who was my buddy throughout the US Navy Underwater Swimmers School experience, was not a huge guy. But we all believed in our abilities, and each other.
John
|
|
|
Post by swimjim on Apr 29, 2010 17:47:38 GMT -8
The military harness is very comfortable underwater and is the closest thing to being a manfish as Cousteau describes. That is, if it is set up correctly. You must configure it with a quick release at all points or it becomes a death trap. I suspect you are referring to the diver who claimed that the chest strap was to tight and preventented him from breathing properly. If a quick release is set up correctly, a sharp tug will release it, not tighten it. The person thought that the salt water swelled the straps preventing this from happening. I have dove these harnesses in warm salt water, the springs in Florida and the cold water lakes in the midwest. A release jamming due to swelling simply does not happen. It was either configured like an old fashioned water ski belt or the diver pulled on the loop instead of the metal tab causing the end to be pulled out of the D-ring and the system to fail. If you can feel the metal tab and pull it the system will release. It will not tighten. If set up like a water ski belt it will tighten and will be damn hard to get un done as described in his post. I know this because I have experienced it first hand. I was flamed for pointing this out, but if you continue to do something which is unsafe you not only off yourself but you give the sport a black eye. YOMV
|
|
|
Post by Linda on Apr 29, 2010 17:56:57 GMT -8
I was flamed for pointing this out... Not here, I hope...
|
|
|
Post by duckbill on Apr 29, 2010 20:33:52 GMT -8
I hear what you're saying, Jim, but I have found some canvas harness straps difficult to undo when wet. 1) If the rings are set close together by the manufacturer, with little or no slack in the loop that holds them, they tend to put a right-angle bight on the pull strap that can be difficult to pull through.
2) Having the harness on tight to begin with seems to lock the rings tighter. I'm one who likes the sternum strap tight, so that's why I know this.
I'd be surprised if James didn't already know how to thread the ends of the straps to make quick-releases.
|
|
|
Post by swimjim on Apr 30, 2010 9:39:08 GMT -8
I would be surprised as well. I have met the mighty Nem and have dove with him. He certainly knows his stuff. However, we all forget things from time to time, myself included. I think that may have been what happened here. Or more likely he was in a hurry to get in the water and simply brain farted. over confidence will get you too.
|
|
Deleted
Deleted Member
Posts: 0
|
Post by Deleted on Apr 30, 2010 14:54:02 GMT -8
However, we all forget things from time to time, myself included. I think that may have been what happened here. Or more likely he was in a hurry to get in the water and simply brain farted. over confidence will get you too. Yep, many a seasoned diver, pilot, race driver, chute jumper, etc. do themselves in by the bugaboo " rushing to error, due to over confidence".........happens to the best......some just get lucky and survive......most don't.......
|
|
|
Post by duckbill on Apr 30, 2010 15:18:51 GMT -8
LOL! I have to admit, I had a "brain fart" at the beginning of the dive season last year regarding this very issue. After an unusually long winter (7 months) I couldn't remember how to correctly lace the straps for the quick release feature even though I had been tying it with no problems, ever, up to that point. I think it must be an age thing. We get rusty faster the older we get! One of these days I will have to resort to the books each Spring just to remember!
Anyhow, I think I should clarify something I said earlier. I mentioned how the problem of stuck straps can be due to the rings being within too small a loop. That was on an original harness I have. I have never had that problem with any of simonbeans Allan's reproduction harnesses. IMO, his are often better than the originals in many ways! I just wanted to say that, lest anyone think I was referring to his harnesses. I've had no problems with tight straps on his harnesses. When I did have a minor, unrelated problem, he was very good at making it right. His customer care is one of the best I've ever experienced.
|
|
|
Post by SeaRat on Apr 30, 2010 16:16:20 GMT -8
I'm going to say a few things here that may be different from what you've heard before. One is that the only military harness I have experience with are the ones I got in the USAF, which were USD harnesses and made of nylon. They also had a metal end clamped (black brass, I believe) on the end of the strap. This helps keep the strap from being pulled through the D-rings as easily.
My feeling is that the nylon does not swell like cotton, and so behaves differently. When cotton swells, it is probably possible to make them not adjust so easily, and possibly not release so easily too. I have not made any tests, but know that the nylon harnesses do not have that problem.
Finally, one other factor that has not been mentioned here is that this particular incident involves a diver with some arthritis in his hands. This affects grip strength, and could affect the ability to adjust the harness in the water.
One other thing--nobody anywhere has mentioned; I wear a silver necklace that my parents-in-law gave me as a wedding present over 33 years ago. I still have it, but it has been in the loop of the chest strap twice, and had to be carefully extracted so that no damage occurred.
John
|
|
|
Post by duckbill on Apr 30, 2010 21:04:20 GMT -8
I have a military harness on my 38s with the stiff nylon straps. They don't swell like the canvas, but the canvas is more supple and comfortable. John, all my military harnesses have just the double D-rings and bare, cut strap ends. I'd be interested in knowing more about the additional hardware you mentioned.
I wear my military dogtags for identification whenever I dive, but I never get them tangled in the straps because I wear them inside my wetsuit.
|
|
|
Post by SeaRat on Apr 30, 2010 21:38:31 GMT -8
Duckbill, About the neckless--it's fine when I'm in open water in my wet suit. But I go into the pool, and don't wear a wet suit there. I also practice doff-and-don exercises, and that's where it gets tangled. I like your idea of the dog tags. Maybe I should start doing something like that when I'm solo diving. But, when I'm solo diving I'm coming back too On the hardware on the end of the military harness straps, I've had one or two now fall off after about 30 years of use. They are a solid brass, shaped in a "D" shape, with the harness on the flat side. I just tried it, and the end definately keeps the strap from pulling back through the D-rings. I'm rather surprised that the newer harnesses that are custom built don't have them. They were standard on the USD military harness. John
|
|